000
AXPZ20 KNHC 200316
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI JUL 20 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...THE MONSOON 
TROUGH AXIS EXTENDS FROM 08N78W TO 09N85W TO A 1009 MB LOW PRES 
NEAR 08N95W TO 07N100W TO 12N115W TO ANOTHER 1009 MB LOW PRES 
NEAR 07N125W TO 05N130W. THE ITCZ AXIS IS FROM 05N130W TO 
08N140W. SCATTERED MODERATE TO STRONG FROM 05N TO THE COAST OF 
PANAMA BETWEEN 80W AND 83W...AND WITHIN 60 NM EITHER SIDE OF THE 
TROUGH AXIS BETWEEN 117W AND 120W. SCATTERED MODERATE ISOLATED 
STRONG FROM 08N TO 12N BETWEEN 111W AND 115W...AND WITHIN 120 NM 
EITHER SIDE OF TROUGH AXIS BETWEEN 125W AND 130W. 

...DISCUSSION...
A 1035 MB SUBTROPICAL HIGH CENTERED WELL NW OF THE FORECAST AREA 
HAS A RIDGE AXIS EXTENDING SE THROUGH 30N130W TO NEAR 20N115W. 

A PAIR OF 1009 MB LOW PRES SYSTEMS ARE EMBEDDED IN THE MONSOON 
TROUGH. THE EASTERNMOST LOW IS NEAR 08N95W WHILE THE WESTERNMOST 
IS LOCATED NEAR 07N125W. PRES GRADIENT BETWEEN THE BUILDING 
RIDGE TO THE N AND LOWER PRES ALONG THE MONSOON TROUGH IS 
RESULTING IN AN AREA OF NE WINDS 20 KT GENERALLY FROM 10N TO 14N 
BETWEEN 112W AND 122W. THESE WINDS WERE SAMPLED BY A MUCH 
EARLIER 1800 UTC ASCAT PASS. THE SAME SCATTEROMETER PASS 
PROVIDED OBSERVATIONS OF SE WINDS OF 20 KT S OF THE MONSOON 
TROUGH ROUGHLY FROM THE EQUATOR TO 04N BETWEEN 118W AND 122W. 
TROPICAL CYCLONE FORMATION IS NOT EXPECTED IN ASSOCIATION WITH 
THESE LOWS DURING THE NEXT 48 HOURS. BEYOND THIS PERIOD...THE 
GLOBAL MODELS ARE IN GENERAL AGREEMENT IN DEVELOPING A LOW ALONG 
THE MONSOON TROUGH IN THE AREA BETWEEN 90W AND 95W LATE SUN AND 
MON WITH THE GFS THE MOST AGGRESSIVE IN DEVELOPING THIS LOW. 

ELSEWHERE...CROSS EQUATORIAL VERY LONG PERIOD SW SWELLS OF 20-22 
SECONDS WITH SEAS TO 8 FT EXTEND SW OF A LINE FROM NEAR THE 
GALAPAGOS ISLANDS NW TO 15N125W. THESE SWELLS WILL SPREAD ACROSS
THE FORECAST AREA OVERNIGHT AND BEGIN TO IMPACT THE COAST OF 
MEXICO...CENTRAL AMERICA AND BAJA CALIFORNIA ON FRI. THE 
POTENTIAL EXISTS FOR LARGE BREAKING WAVES AND DANGEROUS RIP 
CURRENTS ALONG THE COAST INTO THE WEEKEND AS THE SWELL TRAIN 
SLOWLY SUBSIDES. 

GAP WINDS OF 20 KT...WITH DIURNAL PULSES TO 25 KT ARE EXPECTED TO 
CONTINUE OVER THE GULF OF PAPAGAYO AS FRESH TO STRONG TRADE WIND 
FLOW IN THE SW CARIBBEAN FUNNELS THROUGH THE GAP. THE WINDS ARE 
GREATEST DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE 
ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. THIS WILL BUILD SEAS 
TO 9 FT ON FRIDAY. 

THE TROPICAL WAVE CURRENTLY MOVING ACROSS SE MEXICO WILL FORCE 
NLY WINDS OF 20-25 KT THROUGH THE GULF OF TEHUANTEPEC BEGINNING 
LATE FRI AND CONTINUING INTO SAT.

$$
COBB